Isolating switch with particular toggle and interlock means therefor

ABSTRACT

A two-speed operating mechanism is provided for an isolating switch construction, which provides high-speed contact opening for good arc interruption, and low-speed contact movement when the contacts are engaged to minimize operating effort. A novel toggle-mechanism construction is provided, in conjunction with a spring-loaded panel assembly, to effect desired holding of the operating mechanism in both the &#39;&#39;&#39;&#39;ON&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;OFF&#39;&#39;&#39;&#39; positions to prevent thereby contact operation by the application of shock, vibration, or other external forces to the moving contact assemblies. By a novel travel movement, automatic alignment of the movable isolating contacts with the stationary isolating contacts is automatically achieved. A manually-operable handle mechanism with an improved latch is arranged to be mounted on the front of an operating cabinet enclosing the isolating switch mechanism, so that several cabinets may be mounted side-by-side in flush contiguous arrangement.

[ ISOLATING SWITCH WITH PARTICULAR TOGGLE AND INTERLOCK MEANS THEREFOR 75 Inventor: Alfred w. Hodgson, Orchard Park,

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Dec. 21, I972 [21] Appl. No.: 317,330

Related US. Application Data [63] Continuation of Ser. No. 138,143, April 28, 1971,

abandoned.

[52] US. Cl 200/153 G, 200/50 A, 200/153 SC, 335/171 [51] Int. Cl.... H01h 3/46, l-10lh 31/06, Hlh 21/40 [58] Field of Search 200/50 A, 50 C, 153 G, 200/153 H, 153 SC; 335/191, 188, 171

[56] References Cited UNITED STATES PATENTS 3,229,056 1/1966 Turnbill 200/50 A 3,059,072 /1962 Mekelburg et al.... 200/50 A 3,122,615 2/1964 Chace.. 200/50 A 3,163,725 12/1964 Zeller..... 200/153 H X 2,794,881 6/1957 Frank 335/171 X Apr. 2, 1974 2,849,555 8/1958 Cellerini 200/ A Primary E. mminerl-lerman Hohauser Assistant Examiner-Robert A. Vanderhye Attorney, Agent, or Firm-W. R. Crout ABSTRACT By a novel travel movement, automatic alignment of the movable isolating contacts with the stationary isolating contacts is'automatically achieved.

A manually-operable handle mechanism with an improved latch is arranged to be mounted on the front of an operating cabinet enclosing the isolating switch mechanism, so that several cabinets may be mounted side-by-side in flush contiguous arrangement.

9 Claims, 39 Drawing Figures TO CONTACTOR I3 PAIENIEDAPR 2 I974 sum 01 II 12 CLOSED FIG..3VI

' INVENTOR Alfred W. Hodgson ATTORNEY -'ATENTE[] APR 2 I97 sum 02 of 12 CLOSED FIG.

PATENIEUAPR 2 m4 saw on HF 12 FIG. 7

FIG. ICA

I FIG. IO

PAIENIEUAPR 2 I974 sum 07 0F '12 OPEN POSITION FIG. 22

*MENTEDAPR 2W, 7 330L765 sum as DF 12 57 88 v 35 CLOSED POSITION TO l2 CONTACTOR l3 MIENIEDAPR 2 m4 3Q80l 765 SHEET [)9 BF 12 INITIAT OF OPENING RATION JATENTEDAPR 2:914 3.801.765

sum 10 HF 12 CONTINUATION OF OPENING OPERATION TO CO NTACTOR I3 VHENTEUAPR 2 1974 saw 11 HF 12 a: Im m m \u 4/4? 9 m 9 O 7 8 5 2 l I 7 n; m 7 W Y nu 7 7 2 m m w 2 6 .RN 7 M G F DO HANDLE "OFF" 000R CLOSED HANDLE UNLATCHED HANDLE "oFF" DOOR OPEN HANDLE LATCHED IIOFFII switch is usually of a non-load-break ISOLATING SWITCH WITH PARTICULAR TOGGLE AND INTERLOCK MEANS THEREFOR CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation of application Ser. No. 138,143 filed Apr. 28, 1971, now abandoned.

BACKGROUND OF THE INVENTION Motor starters and other feeder circuits are usually supplied with some sort of manually-operated isolating switch, which may be opened to isolate the particular circuit from its source of power without having to deenergize the main power supply. Such an isolating device, but may be of the load-break type. Although such a switch may be classified as a non-load-break device, and is not required to interrupt rated current, it is, however, nevertheless quite often required to interrupt auxiliary loads, such as a control-transformer primary current, static exciter loads, etc., so that good are interruption is still desirable. Such a switch, additionally, may be mounted either in the same enclosure as the motor starter, or at some remote location, and will be referred to herein as an isolating switch," but is also commonly known as a disconnect switch, or sometimes as a safety switch in the electrical industry, as well known by those skilled in the art.

Switches of this type are available from numerous sources, and employ various designs ranging from low cost to expensive, but all of the known designs to me have many or all of the following shortcomings:

l. Expensive design and-construction.

This type of switch may include special individual insulators for each phase and complicated contact details.

The operating mechanism in addition use shafts, bearings, linkages, guide rails, handles, etc., which employ expensive forms of construction.

2.-Equipment is too large for its rating.

3. Equipment is not suitable for panel mounting.

4.-The contacts are not self-aligning.

5. Operating handle projects from the side of the enclosure, which prevents mounting the enclosure tightly against other equipment.

Y 6. When the operating handle is mounted on the front of the enclosure, it must be mounted a fixed distance in front of the isolating switch, which quite often means the isolating switch must be mounted at a different level than the starter panel.

7. The operating handle mechanism is not suitable for dustite or weatherproof applications.

8. Isolating switch contacts are not visible, as required by some regulations and specifications.

9. Electrical interlocks and provisions for mechanical interlocking with the enclosure door, or other devices within the enclosure are not available.

10. Operational defects:

A. The mechanical advantage between the handle and contacts is the same when contacts are engaged as when contacts are moving through air to interrupt an arc. This is not an ideal situation since it will usually result in either low opening speed or a switch, which requires considerable force to .close.

B. The operator may go away and leave the operating handle in a position, which does not provide full contact force or does not provide a safe contact gap.

C. Snap-action is not available on contact opening.

D. Contacts may unintentionally be opened or closed from within the enclosure without operating the handle. This may be due to mechanical shock or vibration, or by accidental contact with certain parts of the isolating switch or operating mechanism by maintenance personnel.

B. When an electrical interlock is provided for automatically unloading the isolating switch before the isolating switch contacts are opened, the interlock contacts do not usually open far enough in advance of main contact opening to allow an auxiliary relay or contactor to drop out and unload the isolating switch contacts before the isolating switch contacts open.

F. Theinherent design is such that excessive operating friction is difficult to remove from the contact assemblies and/or the operating mechanism.

SUMMARY OF THE INVENTION In accordance with the invention in one form, there is provided an isolating or disconnecting switch comprising a movable contact carrier carrying the movable isolating contacts of the switch. The carrier is pivotally mounted to a rotatable actuating arm, which carries a spring and is pivotally mounted to the side support of the switch. The arrangement is such that a manuallyoperated handle assembly and linkage effects positive rotation of the actuating arm and carrier, which through a novel toggle mechanism and a biasing-spring construction, insures high-speed contact opening for good are interruption, and low-speed contact movement when the contacts are engaged during closing to minimize the manual operating effort required.

Preferably, the operation of the manually-operated isolating switch is properly coordinated with a electrically-actuated series contactor, so that the contactor is de-energized prior to the opening of the isolating switch of the present invention.

It is, accordingly, a general'object of the present invention to provide an improved isolating, or safety switch for motor starters or other feeder circuits.

Still a further object of the present invention is the provision of an improved toggle-type of operating mechanism for a safety switch.

Still a further object of the present invention is the provision of an improved toggle-operating mechanism for a safety switch, utilizing in conjunction therewith a spring-loaded pawl assembly to ensure an overcenter holding of the switch contacts in both the open and closed-circuit positions thereof.

Still a further object of the present invention is the provision of an improved safety-switch construction involving few parts, and requiring no precise alignment of the several components parts.

Another object of the present invention is the provision of an improved safety switch, in which the movable isolating contacts are automatically aligned with the stationary isolating contacts by a simple construction.

Another object of the present invention is the provision of an improved operating mechanism for a safety switch, in which a dead-center condition is achieved in both the ON and OFF positions of the switch, so that the contacts are locked in both of these positions, to thereby prevent contact operation by the application of shock, vibration, or other external forces, which might act on the moving-contact assembly.

Still a further object of the present invention is the provision of an improved safety switch, orisolating switch, which may be adapted for 1,500 volt potentials, and with insulation distances in conformity with NEMA requirements.

Yet a further object of the present invention is the provision of an improved handle-operating mechanism and door latching arrangement for a safety switch.

Another object of the invention is the provision of an improved isolating switch, manually operated by a handle, such that when the handle is in the OFF position, the operating rod, connecting the switch assembly with the operating handle, is past dead" center, so that the handle is forced tightly against the OFF position stop, when force is applied to close the moving contact assembly, rather than allowing the contacts to be pushed to the closed position.

An auxiliary object of the invention is the provision of an improved safety switch, in which when the handle is moved from the OFF position to the contact touch position, the mechanical advantage between the handle and contacts is small, and the contacts will thereby travel at maximum speed.

A further object of the present invention is the provision of animproved safety-switch construction, in which the mechanism is arranged so that just prior to reaching the contact touch point, the mechanical advantage of the system increases abruptly to reduce the handle force necessary to engage the contacts.

Yet a further object of thepresent invention is the association of a novel cam mechanism, in conjunction with the toggle-operating mechanism ofa safety switch, so that a spring-loaded pawl roller, acting on the slope of the cam plate assembly, acts to hold the main contacts of the isolating switch in the closed-circuit position.

Another object of the present invention is the provision of an improved toggle-type operating mechanism for a safety switch, which is manually actuated by a handle, in which, when the handle reaches the ON position, and the main contacts are closed, the movingcontact assembly is past a dead center point, so that the main contacts cannot be opened by exerting force upon the moving contact assemblies tending to effect their opening. 7

Another object of the present invention is the provision of an improvedsafety switch, which is manually operated by a handle, in which, when the handle is moved from the ON position to the OFF position, the moving contact support will travel through its dead center area, during which time the main contacts will remain fully closed, but an electrical interlock is opened by the rotating cross-bar assembly directly, so that it will thereby open immediately to thereby deenergize the series electrically-actuated line contactor before the main isolating contacts start to separate from the stationary isolating contacts.

Another object of the present invention is the provision of an improved toggle-operating mechanism for a safety switch, utilizing in cooperation therewith a toggle spring to initiate opening action, and subsequently following collapse of the toggle a spring-biased pawl roller assembly completes the remainder of the opening operation.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an enclosed isolating switch embodying the'principles of the present invention, and the handle of the device indicating the equipment to be in the open or OFF position;

FIG. 2 is an enlarged view looking into the front of the safety-switch enclosure with the'door open and various parts of the enclosure omitted for clarity and with the movable isolating contacts being indicated in the closed-circuit position;

FIG. 3 is an end elevational view of the safety-switch mechanism illustrated in FIG. 2, looking in from the left, substantially along the line III-III of FIG. 2, again the isolating contacts being illustrated in the closedcircuit position;

FIG. 4 is an end elevational view of the improved safety-switch mechanism of the present invention taken in conjunction with the operating-handle mechanism and linkage, looking in the right of FIG. 2 substantially along the line IV-IV of FIG. 2, the isolating contacts being again illustrated in the closed-circuit position, with the manually-operable handle shown in its upward closed position;

FIG. 5 is a front elevational detailed view of the metallic isolation switch movable contact carrier;

FIG. 5A- is atop plan view of the movable carrier of FIG. 5;

FIG. 6 is a view looking in at the left-hand end of the movable contact carrier of FIG. 5 substantially along the line VI-VI of FIG. 5 v

FIG. 7 is an end view looking in at the right-hand end of the contact carrier of FIG. 5 substantially along the line VII'VII' of FIG. 5;

FIG. 8 is a front elevational view of the movable stabbase block assembly, carrying the movable isolating contacts of the device;

FIG. 9 is a detail sectional view taken substantially along the line IXIX of FIG. 8, illustrating the mounting arrangement for the movable isolating contact fingers, whereby a precise alignment thereof is rendered unnecessary;

FIG. 10 is a front elevational view of the movable carrier yoke utilized in the improved mechanism of the present invention;

FIG. 10A is an end side view of the carrier yoke illustrated in FIG. 10 looking in from the right of FIG. 10;

FIG.'11 is a detailed view of the mechanism cam plate, which is utilized in the improved switch mechanism of the present invention;

FIG. 12 is a detailed view of the cam crank assembly utilized in conjunction with the improved handleoperating mechanism of the present invention;

FIG. 13 is a side elevational view of the crank assembly of FIG. 12;

FIG. 14 is'a detailed view of the door latch interlock assembly utilized in conjunction with the improved handle mechanism of the present invention;

FIG. 15 is a detailed end elevational view of an interlock plate of the door latch interlock assembly of FIG. 14;

FIG. 16 is a side elevational view of the metallic sideplate utilized in the stationary frame pivotally supporting the movable contact carrier;

FIG. 16A is an end edge view of the side-plate of FIG. 16 taken along the line XVlAXV1A of FIG. 16.

FIG. 17 is a top plan view of the movable cam block utilized in the improved mechanism;

FIG. 18' is a side elevational view of the cam block of FIG. 17;

FIG. 19 is a detailed side elevational view of the one of the two side plates constituting the interlock lever assembly;

FIGS. 20 and 21 are detailed views of the pawl lever stationary compression-spring bracket;

FIG. 22 is a somewhat diagrammatic and simplified view of the switch mechanism and handle position in the switch-open condition;

FIG. 23 is a view similar to FIG. 22, but illustrating I the closed position of the isolatingswitch, with the handle in the upward ON position;

FIG. 24 is a diagrammatic view, similar to that of FIGS. 22 and 23, but illustrating the initiation ofa contact-opening operation by an initial downward movement of the handle assembly; 7

FIG. 25 is a progressive-further view illustrating the handle mechanism in a continued opening operation during a switch-opening operation;

FIG. 26 illustrates the handle-operating mechanism in the OFF" position, with the door open, and the handle latched in the OFF position by the, latch pin;

FIG. 27 is a sectional plan view taken along the line XXVII-XXVII of FIG. 26;

FIG. 28 illustrates a condition in which the handle mechanism is' in the OFF position, with the door closed, and showing how the handle latch is released by the door-hook plate;

FIG. 29 is a sectionalplan view XXIX-XXIX of FIG. 28;

FIG. 30 illustrates a condition-of the handle mechanism in which the door is closed, and the handle is in the ON" position showing, that the door is latched closed by the latch pin;

FIG. 31 isa sectional plan view XXXl-XXXI of FIG. 30

FIG.- 32 illustrates a typical wiring'diagram' utilizing the improved safety-switch device of the present inventron;

,FIG. 33 is an enlarged side elevational detail view of the movable door hook plate;

FIG. 34 is a top plan view of the movable door hook plate of FIG. 33;

FIG. 35 is an end elevational view ofthe movable door hook plate of FIG. 33, looking in from the right on FIG. 33; and,

FIG. 36 is an enlarged sectional plan view taken generally along the line XXXl-XXXI of FIG. 30.

DESCRIPTION OF THE PREFERRED EMBODIMENT taken along the line taken along'the line ing switch to meet the aforesaid, 1,500-volt specification rating. Such a device may be utilized. For example, for deep-well pumping for 1,500-volt application, whereas, formerly, 600 volt applications were the highest voltage rating achievable in the industry.

As illustrated in FIG. 1, the enclosed equipment 1 includes a cabinet, or casing2, a door 3, which is hinged at 4, Sand 6 as shown in FIG. 1. The door 3 has a pair of latching handles 7 and 8, which are utilized to secure the door 3 into a closed position, as shown. A padlock (not shown) may be used with each latching handle 7, 8 as desired. In addition, the handle 9 itself may be padlocked, if desired either in the ON or OFF position.

With reference to FIG. 1, it will also be observed that a rotatable manually-operable switch-operating handle 9 is provided, which is illustrated in FIG. 1 in the down off position. As will be brought out more fully hereinafter, the handle mechanism 9 is utilized to effect opening and closing operations of the isolating, or disconnecting switch 11, more fully illustrated in FIGS. 24 of the drawings. Provided in series relationship with the isolating, or disconnecting switch 11 is an electrically-actuated magnetic contactor 13 having circuit connections 15-17, which are more clearly illustrated in FIG. 32 of the drawings. As well known by those skilled in the art, the magnetic contactor 13 is electrically opened and closed by pushbuttons, which are accessible from outside the cabinet casing 2, as shown in FIG. 1, and are respectively designated by the reference numerals 20 and 21. As will be obvious, instead of a magnetic contact 13, a motor starter of the type set forth in US. Pat; Nos. 3,264,432 I-Iodgson et al., and 3,290,468 Clark Jr. et al. may be utilized in substitution of the contactor l3.

The equipment, illustrated in FIG. 1, additionally includes a control circuit 22, 23' (FIG..32), which may,

for example, be volts, three magnetic overload relays 25, 26, 27 (FIG. 32), a recording ammeter with a seven-day clock 29, as illustrated in FIG. 1, and, if desired, an undercurrent relay. Additionally, fuses 31, 32, 33 may be included in theseries connections between the isolating, or disconnecting switch 11 and the lowerdisposed electrically-actuated contactor 13, as somewhat illustrated in FIG. 32 of the drawings.

With reference toFIGS. 24 of the drawings, which illustrates the structure and interrelationship between the handle mechanism 34 and the movable contact carrier 35' for the movable isolating contacts 36 of the isolating switch 11, it will be observed that there is provided a metallic base plate, 37, having edge flange portions 37a which is bolted to the back wall 39 of the cabinet 2'. Extending frontwardly from the metallic base plate 37 are two metallic side plates 41, each of which has a configuration more clearly illustrated in FIGS. 16 and 16A of the drawings. A pair .of machine bolts 43 and 44 fixedly secure the two side plates 41 to the side shoulder portions 37a of the back base plate 37, as shown in more detail in FIGS. 2, 3 and 4 of the drawings.

With reference to FIGS. 2 and 3, it will be observed that the two side plates 41 have a pair of integrallyformed tabs 41a and 41b extending in the same direction, which serve to mount a metallic horizontal bracing strip 46, which supports an insulating line terminal block, generally designated by the reference numeral 48. The insulating terminal block 48 fixedly secures into place the three line terminals L L and L the lower ends of which extend downwardly, and constitute three relatively stationary isolating contacts, designated by the reference numerals 50, 51 and 52.

Making separable opening and closing engagement with the three stationary isolating contacts 50, 51 and 52 are three pairs of movable isolating, or disconnecting contact fingers 36, the latter being mounted within an insulating movable contact carrier 54, (FIG. 8) the latter being aff xed, as by bolting at 55, to upper rearwardly-extending flange portions 57a of a suitablyformed movable metallic contact carrier 57 having a configuration more clearly shown in FIGS. -7 of the drawings.

-As illustrated in FIGS. 5 and 6, the metallic contact carrier 57 has a pair of apertures 57b formed therein, which serve to provide mounting holes fora strip-like interlocking bar, designated by the reference numeral 56, and having a rearwardly-extending plunger 58 fixedly secured thereto, as shown more clearly in FIG. 3 of the drawings. The plunger 58 serves to open an interlocking switch 60, which is mounted to the left-hand metallic side-plate wall 41, as shown more clearly in FIGS. 2 and 3 of the drawings. Thus, when the isolating switch 11 is closed, the plunger 58 will effect closing of the contacts 62 of the interlocking switch 60 to thereby complete the electrical closing circuit 64 (FIG. 32) to the lower-disposed magnetic I contactor, or motor starter 13, as the case may be.

As shown in more detail in FIGS. 22-25 of the drawings, the metallic contact carrier 57 has pivot apertures 57c provided at the lower tab portions 57d of the side edges thereof, as illustrated 'in FIG. 5. Floating pivot .pins 66 pivotally connect the metallic contact carrier 57 to the end rotatable actuating arms 68a of a generally U-shaped crossbar structure, designated by the refefrence numeral 68, and more clearly illustrated in FIGS. and 10A of the drawings. In more detail, with reference to FIGS. 10 and 10A of the drawings, the U- shaped crossbar structure, or rotatable actuating arm 68 is provided with pivot apertures 68b to accommodate the floating pivot pins 66. In addition, the U- shaped cross-bar structure, or rotatable actuating arm is provided with supporting pivot apertures 68c to accommodate stationary pivot screws 69, which also pass through stationary pivot apertures 41b (FIG. 16) provided in the two stationary side metallic plates 41 of the switch frame. l

v The pivotal connection of the metallic contact carrier 57 with the U-shaped crossbar structure 68 by the floating pivot connection 66 constitutes a toggle, designated by the reference 71, having the knee joint 66, and more fully described hereinafter.

A biasing tension spring 70 is provided having one end 70a thereof hooked to an aperture opening 68d (FIG. 10) of the bight portion of the U-shaped crossarm 68, and has the other end 70b of the biasing tension spring 70 secured to a movable support pin 72 (FIG. 2), which is bolted to the movable contact carrier 11, is fixedly bolted by a bolt 75 to the movable crossbar arm 68 as shown in FIG. 2, and has a pivotal connection 74a to an operating rod 76, which extends laterally interiorly of the cabinet 2, and is pivotally mounted to a segment-shaped crank plate 78, which is fixedly keyed to'the shaft 80,.which is rotated by the operating handle 9.

In more detail, the handle crank assembly comprises the two spaced crank plates 78 welded to a sleeve 79 (FIG. 12) having a key hole 79a, which is key-primed to the handle-operating shaft 80. Thus, when the handle 9 is manually rotated, the handle arms 9a, affixed to the external outer sides of the handle-operating shaft 80, effect the rotation thereof, as shown in FIGS. 22-31. A handle housing 81 provides opening and closing stops 83, 85 to limit the opening and closing rotative, motion of the manually-operable handle 9, as more fully described hereinafter.

FIGS. 22-25 generally illustrate the different positions of the extemally-provided operating handle 9 relative to the positions of the movable contact carrier 35 for the isolating switch 11. Generally, as the operating handle 9 is moved in a counterclockwise direction from the lower OFF position to the upper ON position, the movable cross-bararm or rotatable actuating arm 68 is rotated in a clockwise direction about the fixed pivot 69, to first rotate the entire contact assembly 84 in a counterclockwise direction'about the fixed pivot pin, 69, until the wear pad, designated by the reference numeral 86, hits the cam surface 88 (FIG. 16) on the side of the side plate 41 of the isolating switch frame 90. This position is illustrated in FIG. 25. When this occurs, continued counterclockwise rotation of the crossbar arm 68 effects a straightening of the toggle mechanism 7l, as illustrated in FIG. 23, thereby raising the three isolating contact fingers 36 upwardly to make firm engagement with-the three relatively'stationary isolating, or disconnecting contacts. 50, 51 and 52. The closed position, of the switch is illustrated in FIG. 23 of the drawings. I

The present invention results in an isolating switch 11, which is compact, lightweight and employing lowcost component parts throughout the construction thereof. Salient operating features of the present isolating, or disconnecting switch 11 are described hereinafter in the order of their occurrence in moving from Y the OFF to the ON position, and then from the ON position to the OFF position.

When the handle 9 is in the OFF position as shown in FIG. 22, the operating rod 76, connecting the switch assembly 11 with the operating handle 9, is past dead center, so that the handle 9 is forced tightly against the OFF position stop 85 when closing force is applied to the moving contact assembly 84, rather than allowing the contacts 36 to be pushed closed. As the handle 9 is moved from the OFF position toward the contact-touch position, the mechanical advantage, between the handle 9 and contacts 36, is small, and the contacts 36 travel at maximum speed in the closing direction.

Just prior to reaching the contact-touch point, as shown by the dotted lines of FIG. 22, the mechanical advantage of the system increases abruptly, to reduce thereby the handle force necessary to engage the contacts 50, 51, 52. In the closing direction, this change in mechanical advantage is accomplished, as indicated in FIG. 22, when the nylon wear pad 86 on the moving contact assembly 84 engages the cam surface 88 on the side plate 41 of the isolating switch frame 90.

The cam 88 is shaped so as to force the tips of the moving contact fingers 36 to follow a linear path up- .wardly. At the same time, the rotating arms 68a of the crossbar 68, acting in conjunction with the moving contact support 35, form a toggle linkage 71, which effects a rapid increase in mechanical advantage, which is maximum when the pivot point66 between these two assemblies approaches dead center. In the closedcircuit position of the isolating switch 11, as shown in FIG. 23, a spring-loaded pawl roller 98, acting on the slope 74a of the cam plate 74, acts to hold the main contacts 36 in the closed position. When the handle 9 reaches the ON position, and the main contacts 36 are closed, the moving contact assembly 84 is past a dead center point, so that the main contacts 36 cannot be opened by exerting force on the moving contact assemblies 84. In this position, the electrical interlock contacts 62 are closed to permit energization of the contactor coil 100 (FIG. 32), which, in turn, results in the flow of load current through the isolating switch 11.

When the handle 9 is moved from the ON position 7 toward the OFF" position, as shown in FIG. 24, the

'main contacts 36 start to separate from the stationary contacts 50, 51, 52. As the handle 9 is moved farther, the main contact fingers 36 will start to slide along the stationary contacts 50, 51 and 52. After a small amount of this contact movement, the pawl roller 98 will ride up on top of the circumference 74b of the cam plate 74 to eliminate any farther closing force by the pawl roller 98 and at the same time the movingcontact bias spring 70 will move past its dead center point to exert an opening force on the operating mechanism, which, in turn, will drive the contacts 36 open to a small contact bracket 99 (FIGS. 20, 21).

The pawl roller assembly 98 performs a number of functions. First, as mentioned hereinbefore, in the closed position of the switch, as shown in FIG. 23, the

gap, even though the operator may have released the handle 9. At this point, the opening force exerted by the bias spring ceases, but the pawl roller 98 then starts to descend-a second slope on the cam plate 74 to drive the main contacts 36 to the open-gap position without assistance by the operator. In addition to the abovementioned' spring forces, the net gravitational forces also act to help open the switch 11. On opening, the mechanical advantage between the handle 9 and the main contacts 36 will change abruptlyfrom a high ratio to a low ratio shortly after the contacts 36 separate, which, in turn, results in rapid opening of the contacts 36.

The net effect of the foregoing operational steps, in a normal operation, is a high-speed snap-action opening, which is recognized as an important aid to are interruption, as well as preventing the operator from leaving the handle 9 at some position between ON and OFF, corresponding to dangerously low-contact forces or an unsafe contact gap.

PAWL ROLLER ASSEMBLY The pawl roller assembly 98- comprises a lever 98a pivoted at 98b on a stationary pivot. The pawl roller pawl roller assembly 98 holds the contacts in the closed position. Secondly, following collapse of the toggle mechanism 71, the spring-biased pawl roller assembly completes the remainder of the opening operation. Thirdly, in the fully open position of the switch 11, as shown in FIG. 22, it holds the switch contacts open.

HANDLE INTERLOCKING MECHANISM (34) Mechanical interlocking is provided between the operating handle 9 and the enclosure door 3 to accomplish the following, as illustrated in FIGS. 22 through 31.

I. To prevent closing of the isolating switch 11 when the enclosure door 3 is open.

2. to prevent opening of the enclosure door 3 when the isolating switch 11 is closed.

In certain instances, however, it is necessary for maintenance personnel to override these safety features, and this is accomplished as follows:

1. The latch pin 87 of FIG. 27 is pushed out of the way by hand to allowthe isolating switch 11 tobe closed, while the enclosure door 3 is open.

2. To open the enclosure door 3 while the isolating switch 11 is closed, the mounting screws 89 for the door-hook plate of FIG. 29 may be removed from the front of the door 3 to disengage the hook 95 from the door 3, or, alternatively, the handle-mechanism housing bolts 101 (FIG. 4) may be removed, and the housing 81 and the mechanism assembly 34 lifted vertically, so that the latch pin 87 will clear the book 95 on the enclosure door 3. g

A stationary pin 122 is supported by screws 123 (FIG. 36) to an aperture backing plate 124, the latter secured by the bolts 101 to the enclosure flange 125. The pin 122 passes through the apertures 126 in the two side latch plates 107, as shown in FIG. 15, and pivotally supports the latch pin assembly 127. A torsion spring 128 biases the latch pin assembly 127 in a clockwise direction against the backing plate 124, as viewed in FIG. 26. As shown in FIG. 27, the side latch plates 107 straddle the handle crank assembly 129.

With the switch closed and the handle 9 up in its ON" position, as shown in FIG. 4, the operating rod 76 bears downwardly on top of the latch pin 87 and moves the latter into latching engagement with the door book, 95, as shown in FIG. 30. This prevents the door 3 from being opened in the closed position of the switch.

Similarly, in the open position of the switch, as shown in FIG. 26, with the door 3 open, the latching surface 78a of the crank plates 78 make latching engagement with the latch pin 87, as shown in FIG. 26, thereby preventing the closing motion of the handle 9.

When the door is closed, as shown in FIG. 28, a portion 95a of the door hook 95 moves the latch pin 87 forward to clear the latching surfaces 78a of the crank assembly 129 and to permit the handle mechanism 34 to move upwardly to the closed position.

Additionally, there is provided mechanical interlocking between the isolating switch 11 and the magnetic contactor 13 by the interlock arm 102, shown in FIG.

22 carrying a horizontal interlocking pin 102a. When this arm 102 is raised, as shown in FIGS. 22 and 23, the pin 102a prevents rotation of the cam plate 74, thereby locking the isolating switch 11 either in the open or in the closed-circuit positions. When the isolating switch 11 is between the positions, as shown in FIGS. 24 and 25, the interlock arm 102 will be blocked in the lower position by the cam plate 74. The interlock arm 102 is usually actuated by an operating rod 120 pivoted at 121 to the cam plate 74 and attached to the armature assembly of a magnetic contactor 13 in such a manner that the interlock arm 102 will be raised, when the main contacts 104, 105 and 106 of the contactor 13 are closed. Inthis mode of operation, the mechanical interlock will act to prevent opening or closing the isolating switch 11 under load, or applying load when the isolating switch 11 is not fully open or closed.

The various bearings, required by the switch unit, are formed by punching, or drilling holes in certain of the sheet steel details resulting in a bearing with short length. As a result of the short-bearing lengths, a friction-free' mechanism 92 can readily be assembled without special attention being given to the alignment of shafts and bearings. Preferably, the flared moving contact fingers 36a are made from a resilient material, or a spring-type conducting material, such as beryllium-copper alloy, or, for example, phosphor-bronze, loosely held in the moving contact insulator, as more clearly illustrated in FIG. 9, thereby providing a selfaligning contact feature.

CIRCUIT CONNECTIONS FIG.' 32 more clearly illustrates the circuitconnection arrangement of the improved safety, or isolating switch 11 of the present invention in series circuit with the electrically-actuated magnetic contactor 13. With reference to FIG. 32, it will be observed that there is provided a control circuit power supply 22, 23, the circuit line 22 passing through a stop pushbutton 21, which is normally closed, and then through a parallel circuit, comprising a normally-open start button 20, and a parallel contact arrangement, 108 actuated by the opening and closing of the main starter or contactor 13. The circuit 22 then extends through an electrical interlock 60 to the coil 100 of the starter contactor 13 to the other side of the control-circuit power supply 23.

As shown, fuses 31, 32, 33 may be provided serially in the three circuits 15, 16, .17 of the three-phase circuit, extending from the power source L L L to the load circuit v109, 110, 111 (FIG. 32). Additionally, a plurality of overload relays 25, 26 and 27 may be utilized, one about each of the circuits, so that upon the existence of an overload current for an extended period of time, or in the case of an instantaneous heavy overload current, the overload relays 25,26 and 27 will pick up, and open the normally-closed contacts 65a, 65b and 65c, which are serieswith the coil circuit 100.

instead of to the side, which would prevent side-by-side mounting of the cabinets, 2. In addition, the mechanism 92 is such that the toggle 71 is in the overcenter position in both the fully-closed position of the switch 11 and also in the fully open-circuit position thereof. This has the important advantage that a dead-center condition of the operating mechanism 92 in both the open and of positions locks the contacts 36 either open or closed to prevent contact operation by the application of shock, vibration, or other external forces to the moving contact assemblies 84. Moreover, precise alignment of the parts is not necessary to eliminate operating friction.

Although there has been illustrated and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

I claim as my invention:

1. An isolating switch comprising, in combination, a relatively stationary contact, a movable contact carrier carrying a movable contact which makes separable engagement with said stationary contact, a rotatable actuating arm pivotally mounted'on a fixed pivot intermediate the ends thereof, one end of said rotatable actuating arm being pivotally connected to said movable contact carrier, and the other end of said rotatable actuating arm carrying one end of a tension spring, the other end of said tension spring connected to said movable contact carrier at a point removed from the pivotal connection of said movable contact carrier to said rotatable actuating arm, whereby rotary movement of said rotatable actuating arm tensions said tension spring and also changes the direction of the biasing force to effect first a rotation of the entire assembly and subsequently an elongation and straightening of the toggle comprising said movable contact carrier and said rotatableactuating arm."

2. The combination according to claim 1, wherein a fixed stop is provided to halt the rotary movement of the assemblage and then force an extension of said toggle to a contact-closed position.

3. Thecombination according to claim 1, wherein a handle linkage is provided, and the rotation of the handle linkage effects-an actuating rotary closing movement of said rotatable actuating arm.

4. The combination according to claim 1, wherein a cam plate is fixedly secured to said rotatable actuating arm and a spring-biased pawl device moves over the cam surface of the cam plate to provide an opening force.

5. The combination according to claim 4, wherein a portion of said cam plate affords an interlocking surface with a rotatable interlocking arm.

6. Electrical equipment including an isolating switch and a series-related contactor, said isolating switch comprising, in combination, a relatively stationary contact, a movable contact carrier carrying a movable contact which makes separable engagement with said stationary contact, a rotatable actuating arm pivotally mounted on a fixed pivot intermediate the ends thereof, one end of said rotatable actuating arm being pivotally connected to said movable contact carrier, and the other end of said rotatable actuating arm carrying one end of a tension spring, the other end of said tension spring connected to said movable contact carrier at a point removed from the pivotal connection of said movable contact carrier to said rotatable actuating arm, whereby rotary movement of said rotatable actuating arm tensions said tension spring and also changes the direction of the biasing force to effect first a rotation of the entire assembly and subsequently an elongation and straightening of the toggle comprising said movable contact carrier and said rotatable actuating arm, a cam plate fixedly secured to said rotatable actuating arm and having an interlocking cam surface, an operating rod responsive to the opening and closing movement of said contactor, and a rotatable interlocking arm pivotally connected to said operating rod so that when said contactor is closed, it is impossible to effect rotation of the cam plate and consequently rotation of the rotatable actuating arm.

7. The combination according to claim 6, wherein a handle mechanism is provided, and a handle linkage is pivotally connected to said rotatable actuating arm to effect the opening and closing rotative movements thereof.

8. The combination according to claim 6 wherein an electrical interlock switch is provided, and a plunger affixed to and movable with the movable contact carrier effects opening and closing'of said interlock switch.

9 A switch assembly including a switch cabinet and a hinged door therefor, a switch interrupter having a switch mechanism disposed interiorly within said switch cabinet and having a generally horizontallyarranged switch operating rod (76) horizontally movable generally linearly to effect the opening and closing operations of said switch mechanism, a manuallyoperable handle assembly fixedly mounted to the front of the switch cabinet and rotatable in a generally vertical direction, said handle-assembly including a latching plate (78) movable therewith, said generally horizontally arranged switch operating rod being pivotally connected off-center to said latching plate (78) for interrelating handle motion with the switch mechanism operation, means defining a rotatable latch-pin assembly (107, 87 fixedly mounted to the rear side of the switch cabinet and carrying a rotatable latch pin (87), said hinged door carrying a latch hook cooperating with said rotatable latch pin (87) to effect latching of the door when said latch pin (87 is in its down latching position, biasing means for rotating the rotatable latch pin assembly (107, 87) to a releasing position with the latch pin (87) in its upper released position, and said generally horizontally arranged switch operating rod 76) forcing said latch pin (87) downwardly to its latched down position when the switch mechanism is closed. 

1. An isolating switch comprising, in combination, a relatively stationary contact, a movable contact carrier carrying a movable contact which makes separable engagement with said statiOnary contact, a rotatable actuating arm pivotally mounted on a fixed pivot intermediate the ends thereof, one end of said rotatable actuating arm being pivotally connected to said movable contact carrier, and the other end of said rotatable actuating arm carrying one end of a tension spring, the other end of said tension spring connected to said movable contact carrier at a point removed from the pivotal connection of said movable contact carrier to said rotatable actuating arm, whereby rotary movement of said rotatable actuating arm tensions said tension spring and also changes the direction of the biasing force to effect first a rotation of the entire assembly and subsequently an elongation and straightening of the toggle comprising said movable contact carrier and said rotatable actuating arm.
 2. The combination according to claim 1, wherein a fixed stop is provided to halt the rotary movement of the assemblage and then force an extension of said toggle to a contact-closed position.
 3. The combination according to claim 1, wherein a handle linkage is provided, and the rotation of the handle linkage effects an actuating rotary closing movement of said rotatable actuating arm.
 4. The combination according to claim 1, wherein a cam plate is fixedly secured to said rotatable actuating arm and a spring-biased pawl device moves over the cam surface of the cam plate to provide an opening force.
 5. The combination according to claim 4, wherein a portion of said cam plate affords an interlocking surface with a rotatable interlocking arm.
 6. Electrical equipment including an isolating switch and a series-related contactor, said isolating switch comprising, in combination, a relatively stationary contact, a movable contact carrier carrying a movable contact which makes separable engagement with said stationary contact, a rotatable actuating arm pivotally mounted on a fixed pivot intermediate the ends thereof, one end of said rotatable actuating arm being pivotally connected to said movable contact carrier, and the other end of said rotatable actuating arm carrying one end of a tension spring, the other end of said tension spring connected to said movable contact carrier at a point removed from the pivotal connection of said movable contact carrier to said rotatable actuating arm, whereby rotary movement of said rotatable actuating arm tensions said tension spring and also changes the direction of the biasing force to effect first a rotation of the entire assembly and subsequently an elongation and straightening of the toggle comprising said movable contact carrier and said rotatable actuating arm, a cam plate fixedly secured to said rotatable actuating arm and having an interlocking cam surface, an operating rod responsive to the opening and closing movement of said contactor, and a rotatable interlocking arm pivotally connected to said operating rod so that when said contactor is closed, it is impossible to effect rotation of the cam plate and consequently rotation of the rotatable actuating arm.
 7. The combination according to claim 6, wherein a handle mechanism is provided, and a handle linkage is pivotally connected to said rotatable actuating arm to effect the opening and closing rotative movements thereof.
 8. The combination according to claim 6 wherein an electrical interlock switch is provided, and a plunger affixed to and movable with the movable contact carrier effects opening and closing of said interlock switch.
 9. A switch assembly including a switch cabinet and a hinged door therefor, a switch interrupter having a switch mechanism disposed interiorly within said switch cabinet and having a generally horizontally-arranged switch operating rod (76) horizontally movable generally linearly to effect the opening and closing operations of said switch mechanism, a manually-operable handle assembly fixedly mounted to the front of the switch cabinet and rotatable in a generally vertical direction, said handle-assembly including a latching plate (78) movAble therewith, said generally horizontally arranged switch operating rod being pivotally connected off-center to said latching plate (78) for interrelating handle motion with the switch mechanism operation, means defining a rotatable latch-pin assembly (107, 87) fixedly mounted to the rear side of the switch cabinet and carrying a rotatable latch pin (87), said hinged door carrying a latch hook (95) cooperating with said rotatable latch pin (87) to effect latching of the door when said latch pin (87) is in its ''''down latching'''' position, biasing means for rotating the rotatable latch pin assembly (107, 87) to a releasing position with the latch pin (87) in its upper released position, and said generally horizontally arranged switch operating rod (76) forcing said latch pin (87) downwardly to its latched down position when the switch mechanism is closed. 